I inquired whether their tune is compatible with the US-spec 335d (I asked and it is) and yes, they will ship to the US:

"Thanks for your enquiry. I can confirm that the upgrade is carried out in exactly the same way [as the EU/GB-spec 335d]. Unfortunately you would need to post your ecu to us to have your software upgraded as from mid 2009 BMW introduced anti tuning protection which prevents tuning over the diagnostic port."